My previous research has shown that the medial preoptic area (MPOA) is involved in the neural regulation of maternal behavior. The major objective of the present proposal is to investigate the role of the MPOA in the regulation of maternal behavior through its interactions with other neural structures also known to be involved in maternal behavior. The MPOA is involved in the reproductive behavior of several vertebrate species, including primates, but the exact function the MPOA plays in the regulation of such behavior is unclear. It is hoped that the proposed research will provide an answer to this question. The proposal consists of more than 18 experiments and the following techniques will be employed: brain lesioning, knife cuts, electrical stimulution, and application of chemicals to the brain. The rationale underlying the proposed experiments is (1) that the ascending projections of the preoptic region to the limbic system are necessary for the integration of maternal response patterns into an organized sequence and (2) that the descending projections of the reoptic region to the brainstem catecholaminergic systems are necessary for the motivational aspects of maternal behavior. In particular, preoptic influences on the septo-hippocampal system are hypothesized to underlie the efficient organization of maternal response patterns while the preoptic projections to the substantia nigra of the midbrain are hypothesized to influence nonspecific motivational systems necessary for the occurrence of maternal behavior. The experiments are designed to show that destruction of the ascending projections of the preoptic region during the postpartum period will disorganize maternal behavior while disruption of the descending projections should abolish maternal behavior.